Differences in Mechanical and Physicochemical Properties of Several PTFE Membranes Used in Guided Bone Regeneration

Resorbable engineered barrier membranes for oral surgery applications

Population aging, reduced economic capacity, and neglecting the treatments for oral pathologies, are the main causal factors for about 3 billion individuals who are suffering from partial/total edentulism or alveolar bone resorption: thus, the demand for dental implants is increasingly growing. To achieve a good prognosis for implant-supported restorations, adequate peri-implant bone volume is mandatory. The Guided Bone Regeneration (GBR) technique is one of the most applied methods for alveolar bone reconstruction and treatment of peri-implant bone deficiencies. This technique involves the use of different types of membranes in association with some bone substitutes (autologous, homologous, or heterologous). However, time for bone regeneration is often too long and the bone quality is not simply predictable. This study aims at engineering and evaluating the efficacy of modified barrier membranes, enhancing their bioactivity for improved alveolar bone tissue regeneration. We investigated membranes functionalized with chitosan (CS) and chitosan combined with the peptide GBMP1α (CS + GBMP1α), to improve bone growth. OsseoGuard® membranes, derived from bovine Achilles tendon type I collagen crosslinked with formaldehyde, were modified using CS and CS + GBMP1α. The functionalization, carried out with 1-ethyl-3-(3 dimethylaminopropyl)carbodiimide and sulfo-N-Hydroxysuccinimide (EDC/sulfo-NHS), was assessed through FT-IR and XPS analyses. Biological assays were performed by directly seeding human osteoblasts onto the materials to assess cell proliferation, mineralization, gene expression of Secreted Phosphoprotein 1 (SPP1) and Runt-Related Transcription Factor 2 (Runx2), and antibacterial properties. Both CS and CS + GBMP1α functionalizations significantly enhanced human osteoblast proliferation, mineralization, gene expression, and antibacterial activity compared to commercial membranes. The CS + GBMP1α functionalization exhibited superior outcomes in all biological assays. Mechanical tests showed no significant alterations of membrane biomechanical properties post-functionalization. The engineered membranes, especially those functionalized with CS + GBMP1α, are suitable for GBR applications thanks to their ability to enhance osteoblast activity and promote bone tissue regeneration. These findings suggest a potential advancement in the treatment of oral cavity problems requiring bone regeneration.

Adhesion of Candida albicans on PTFE membranes used in guided bone regeneration

OBJECTIVES

Guided bone regeneration (GBR) is a core procedure used to regenerate bone defects. The aim of the study was to investigate the adherence of Candida albicans on six commercially available polytetrafluoroethylene (PTFE) membranes used in GBR procedures and the subsequent clinical consequences.

MATERIALS AND METHODS

Six commercially available PTFE membranes were tested. Two of the membranes had a textured surface and the other four a plane, nontextured one. C. albicans (ATCC 24433) was cultured for 24 h, and its cell surface hydrophobicity was assessed using a modified method. C. albicans adhesion to membrane discs was studied by scanning electron microscopy (SEM) and real-time polymerase chain reaction (PCR).

RESULTS

C. albicans was found to be hydrophobic (77.25%). SEM analysis showed that C. albicans adherence to all membranes examined was characterized by patchy, scattered, and small clustered patterns except for one nontextured membrane with a most rough surface in which a thick biofilm was observed. Real-time PCR quantification revealed significantly greater adhesion of C. albicans cells to PTFE membranes than the control membrane (p ≤ .001) with the membranes having a textured surface exhibiting the highest count of 2680 × 104 cells/ml compared to the count of 707 × 104 cells/mL on those with a nontextured one (p ≤ .001). One membrane with nontextured surface, but with most rough surface was found to exhibit the highest count of 3010 × 104 cells/ml (p ≤ .05).

CONCLUSION

The results of this study indicate that C. albicans adhesion on membranes' surfaces depends on the degree of surface roughness and/or on the presence of a texture. Textured PTFE membranes and/or membranes high roughness showed significantly more adhered C. albicans cells. These findings can impact the surgeon's choice of GBR membrane and postoperative maintenance.

The Performance Testing and Analysis of Common New Filter Materials: A Case of Four Filter Materials

The complex air environment makes it urgent to build good and safe indoor environments, and the study and application of new materials have become the focus of current research. In this study, we tested and analyzed the structural parameters and filtration performances of the four most commonly used new filter materials in the current market. The results showed that all four new filter materials showed a trend of first increasing and then decreasing their filtration efficiency with an increase in filtration velocity. The filtration efficiency of the materials was as follows: PTFE > glass fiber > nanomaterial > electret. The filtration efficiency of all materials reached its maximum when the filtration velocity was 0.2 m/s. The filtration efficiency of the PTFE for PM10, PM2.5, and PM1.0 was higher than that of the other three materials, with values of 0.87% to 24.93%, 1.21% to 18.69%, and 0.56% to 16.03%, respectively. PTFE was more effective in capturing particles smaller than 1.0 μm. Within the testing velocity range, the resistance of the filter materials was as follows: glass fiber > PTFE > electret > nanomaterial, and the resistance of the four materials showed a good fitting effect. It is also necessary to match the resistance with the filtration efficiency during use, as well as to study the effectiveness of filter materials in blocking microorganisms and absorbing toxic gases. Overall, PTFE showed the best comprehensive performance, as well as providing data support for the selection of related materials or the synthesis and research of filter materials in the future.

Unveiling the consequences of early human saliva contamination on membranes for guided bone regeneration

AIMS

GBR membranes have various surface properties designed to elicit positive responses in regenerative clinical procedures; dental clinicians attempt to employ techniques to prevent the direct interaction of contaminated oral fluids with these biomaterials. However, saliva is uninterruptedly exhibited in oral surgical procedures applying GBR membranes, suggesting a persistent interaction with biomaterials and the surrounding oral tissues. This fundamental study aimed to investigate potential alterations in the physical, chemical, and key biological properties of membranes for guided bone regeneration (GBR) caused by isolated early interaction with human saliva.

METHODS

A reproducible step-by-step protocol for collecting and interacting human saliva with membranes was developed. Subsequently, membranes were evaluated for their physicochemical properties, protein quantification, DNA, and 16S rRNA levels viability of two different cell lines at 1 and 7 days, and ALP activity. Non-interacted membranes and pure saliva of donors were applied as controls.

RESULTS

Qualitative morphological alterations were noticed; DNA extraction and 16S quantification revealed significantly higher values. Furthermore, the viability of HGF-1 and MC3T3-E1 cells was significantly (p < .05) reduced following saliva interaction with biodegradable membranes. Saliva contamination did not prejudice PTFE membranes significantly in any biological assay.

CONCLUSIONS

These outcomes demonstrated a susceptible response of biodegradable membranes to isolated early human saliva interaction, suggesting impairment of structural morphology, reduced viability to HGF-1 and MC3T3-E1, and higher absorption/adherence of DNA/16S rRNA. As a result, clinical oral procedures may need corresponding refinements.

The potential of nano graphene oxide and chlorhexidine composite membranes for use as a surface layer in functionally graded membranes for periodontal lesions

Membranes have been used for treating periodontal defects and play a crucial role in guided bone regeneration applications. Nano graphene oxide have been exploited in tissue engineering due to its biomechanical properties. Its composite formulations with hydroxyapatite and chitosan with controlled degradation could aid in becoming part of a surface layer in a functionally graded membrane. The aim of the study was to synthesize chitosan and composite formulations of nano graphene oxide, hydroxyapatite and chlorhexidine digluconate using solvent casting technique and to characterize the physiochemical, mechanical, water vapor transmission rate (barrier), degradation and antimicrobial potential of the membranes. Altogether four different membranes were prepared (CH, CCG, 3511 and 3322). Results revealed the chemical interactions of hydroxyapatite, chitosan and nanographene oxide due to inter and intra molecular hydrogen bonding. The tensile strength of 3322 (33.72 ± 6.3 MPa) and 3511 (32.06 ± 5.4 MPa) was higher than CH (27.46 ± 9.6 MPa). CCG showed the lowest water vapor transmission rate (0.23 ± 0.01 g/h.m2) but the highest weight loss at day 14 (76.6 %). 3511 showed a higher drug release after 72 h (55.6 %) Significant biofilm growth inhibition was observed for all membranes. 3511 showed complete inhibition against A. actinomycetemcomitans. Detailed characterization of the synthesized membranes revealed that 3511 composite membrane proved to be a promising candidate for use as a surface layer of membranes for guided bone regeneration of periodontal lesions.

Evaluation between Biodegradable Magnesium Metal GBR Membrane and Bovine Graft with or without Hyaluronate

Bone substitutes and barrier membranes are widely used in dental regeneration procedures. New materials are constantly being developed to provide the most optimal surgical outcomes. One of these developments is the addition of hyaluronate (HA) to the bovine bone graft, which has beneficial wound healing and handling properties. However, an acidic environment that is potentially produced by the HA is known to increase the degradation of magnesium metal. The aim of this study was to evaluate the potential risk for the addition of HA to the bovine bone graft on the degradation rate and hence the efficacy of a new biodegradable magnesium metal GBR membrane. pH and conductivity measurements were made in vitro for samples placed in phosphate-buffered solutions. These in vitro tests showed that the combination of the bovine graft with HA resulted in an alkaline environment for the concentrations that were used. The combination was also tested in a clinical setting. The use of the magnesium metal membrane in combination with the tested grafting materials achieved successful treatment in these patients and no adverse effects were observed in vivo for regenerative treatments with or without HA. Magnesium based biodegradable GBR membranes can be safely used in combination with bovine graft with or without hyaluronate.